Preparation Steps

• Preheat your oven to 350°F (175°C) and grease a 9x13 inch baking pan.
• In a large bowl, mix melted butter, granulated sugar, and brown sugar until well combined.
• Add the eggs one at a time, mixing well after each addition.
• Sift together flour and cocoa powder, then fold into the wet ingredients until just combined.
• Spread half of the brownie batter into the prepared baking pan.
• Dollop spoonfuls of peanut butter over the batter and swirl lightly.
• Add the mini marshmallows evenly over the peanut butter layer and then pour the remaining batter on top.
• Bake for 30 minutes or until a toothpick comes out clean.
• Let cool before cutting into squares and serving.